Disclosed herein is a vehicle seat, and specifically a vehicle seat with an improved attachment workability of peripheral members to a side frame by reducing the size of a peripheral structure of the side frame.
In the case of a so-called rear end collision in which an end portion of a vehicle such as an automobile is impacted from behind or has a severe collision during backward driving, generally a head of an occupant may be suddenly inclined backward due to the inertia force and his/her neck may be damaged.
Therefore, a seat for a vehicle such as an automobile has a headrest above a seat back to receive the head of the occupant from behind in order to protect the head and the neck of the occupant from an impact load due to rear end collision to reduce the damage on the neck.
However, providing the head rest alone cannot reduce the impact load on the body, and it may also be difficult to sufficiently reduce the impact on the neck unless a gap between the head of the occupant and the headrest is immediately reduced at the time of read-end collision.
To solve this problem, a technique is known in which an impact is effectively reduced by providing a seat back frame equipped with a pressure receiving member for receiving a load of an occupant with a link member movable with respect to the side frame and attaching the link member to the pressure receiving member via a joint member, and thereby sufficiently causing the occupant to sink into the seat back at the time of the collision (see Japanese Patent Document No. 2009-023517 A (“the '517 Document”)).
It is required for the vehicle seat to retain a seating space of the occupant without deformation of the vehicle seat by impact energy upon rear end collision as well as side collision, thereby ensuring safety of the occupant.
As a technique of keeping the safety of the occupant against such a side collision, a technique of arranging a side bracket on a lateral side of the vehicle and also on a door side is disclosed (see Japanese Patent Document 2000-103275 A (“the '275 Document”)). According to this technique, when an impact load is applied from the lateral side, the impact load is transferred to the vehicle seat via a receiving member (side bracket) and tilts the vehicle seat toward the center of the vehicle body without deformation of the vehicle seat, thereby preventing the occupant from contacting a structure of the vehicle body.
The seat back frame disclosed in the '517 Document can sufficiently cause an occupant to sink toward the seat back frame at the time of rear end collision by receiving a rearward movement of the occupant by the pressure receiving member and thus pivoting the link member. Furthermore, because the link member is disposed with a biasing element and the biasing element typically inhibits pivoting of the pressure receiving member, a seating comfort will not be impaired. Moreover, a plurality of stoppers for regulating an allowable moving range of the link member is disposed near the link member, which can regulate the range of sinking the occupant.
According to the technique disclosed in the '275 Document, at the time of a side collision, the load is transferred from a pushing member provided on the vehicle body side to the receiving member (side bracket) arranged to protrude on the lateral side of the vehicle seat (more specifically, the lateral side of the seat back frame), resulting in the vehicle seat tilting toward the center of the vehicle body. Thus, by transferring the impact of a side collision to the vehicle body side, the seating space of the occupant can be ensured in the vehicle seat, thereby ensuring safety of the occupant.
However, when the pressure receiving member having the link member disclosed in the '517 Document and the receiving member disclosed in the '275 Document are provided to the vehicle seat in order to improve the safety against both rear end collision and side collision, a plurality of members are densely arranged on the lateral side of the seat back frame, i.e., in the periphery of the side frame. When many members are arranged in the periphery of the side frame in this manner, due to a large number of the components, it is required to spare a relatively large space on the lateral side of the seat back frame, which disadvantageously reduces the design freedom and reduces the seating space of the occupant, thereby reducing the occupant's comfort.
To counter the disadvantage, if a space reduction is intended by reducing the size of each member, there would be a risk of reducing durability against an impact at the time of rear end collision and side collision because each member is not strong enough. Especially the receiving member (side bracket) laterally protruding from the side frame requires a sufficient strength because it directly receives the impact of a side collision, and it also requires a certain size to effectively transfer the load of a side collision to the vehicle body side.
In other words, it has been difficult to both obtain the strength (rigidity) against rear end collision and side collision as well as reducing the size of the peripheral structure of the side frame. Therefore, a technique for both reducing the size of the peripheral structure of the side frame and providing the peripheral structure of the side frame having a sufficient strength against collision has been desired.
Furthermore, when many members are arranged in the periphery of the side frame, there is a disadvantage that the workability of attachments is impaired because an attachment structure of each member becomes complex due to a large number of the components. Therefore, a technique for improving the attachment workability of the members in the periphery of the side frame in the vehicle seat has been desired.